The point-like nature of the obstacles should not alter the equilibrium distribution of chain conformations while altering the dynamical landscape.
We verify that this is indeed the case by computing the ensemble-averaged end-to-end distance \(\mathbf {R}^2\)  [see Fig. REF (a)].
We find no statistically significant change in the chain conformation upon the inclusion of our point-like obstacles for all chain lengths (with \(d_T=4\) ) and tube diameters (with \(N=200\) ).
In Fig. REF (b), we plot the monomer mean-square displacement (MSD) normalized by \(t^{1/4}\)  – the characteristic power law that is a hallmark of reptation [1]}.
In general, finite chain lengths can obscure observation of the expected reptation dynamics due to the fast relaxation of the chain-ends [2]}.
We therefore average the MSD over the interior \(N_e\)  beads and, in doing so, observe the emergence of a \(t^{0.28}\)  scaling in the MSD on timescales greater than the entanglement blob relaxation time and less than the Rouse time [see Fig. REF (b)].
These findings support the idea that the forces exerted by the obstacles on the chain segments are purely entropic, allowing us to unambiguously explore the role of topological forces.
